Help: 7805 gets very very hot! @ Core Module

[Guest Andre_Raabe]

Hi folks!

my problem is, that my voltage regulator (7805) gets extremly hot...My power supply has only 400mA und i´m going to supply 9 V.

The circuit of the CoreModule seems OK but nothing works probably. (Just testet LCD - which is correct working on another Core Module).

I´ve noticed that my C3 Cap has 22uF than 10 uF but i can´t believe that this has such consequence.

Could a defekt of the transistor a reason?

Cheers!

André

[lemonhorse]

hi André,

i guess the 22uF cap is not the problem.

what is the voltage value on your 7805 input pin? - if you have more then 10V it can cause the heat - in this case you should take a cooling element for the 7805 or another transformer.

power supply:

i made good experiences with 7805 (1A) and a 7.5V (800mA) transformer...

...but maybe it's a circuit problem - in this case you can:

-  check all the soldering joints for short circuit or false connection (i know you have allready but who knows (i found some bugs after chcking the circuit-board about ten times...))

- the next option to find the bug is to remove suspect components step by step from the core modul and check the heat of the 7805 each time - if no component left over check the soldering joints again... ;)

good luck!

- lemonhorse

[LO]

sounds like a short circuit!

put a fuse in-line and see if it blows. Its a good idea to use a fuse until you get everything sussed to save damage on your board